94 w/t 4.3l, 139.339 miles. about 3 weeks ago was in the highway and all of a sudden a backfire, hesitated and backfired again. got to where i was going. got back in truck to go home, everything perfect. no trouble, no hesitation no nothing. 3 weeks went by and yesterday the same thing. sudden backfire, hesitation. today all is normal again. feels like when a carbureted car chokes. my feeling is a mal functioning fuel pump, clogged filter. what you guys think? only thing weird is a strong smell of gas sometimes, not constant, but once in a while.

 

sounding like you has a gas leakin in your intake manny. try looking around reading about the csfi, or spider injection. i myself am replacing the poppet style and going mpi. thats my idea since you say you smell gas at times, and those poppet valves are known for issues. and maybe they are dumping extra gas in the manny and causing it to run rich.

 

cams 98, you got the right idea switching to the mfi. i just did this and wow! amazing improvement. absolutely well worth the money. and if you are mechanically inclined, should only take couple hours. pm me if you need help.


however, on julosibia rig, his is 94 4.3, so it could have scpi, or may still be throttle body injected. julosibia, does the top of your motor say vortec? if it does, you have the same style injectors that cams 98 referred to. the poppet style, which GM has recognized as a problem. upgrading to the mfi is a pretty easy job, and as stated above, well worth the money. however, i would check fuel pressure, change fuel filter, and check to make sure the gas cap is on tight, and making a good seal. these ecm's require a tight cap, and yes, they can tell if it leaks.

 

i do have tbi.and my engine says vortec.